1. Field of Invention
The present invention relates to gas lasers and more particularly to closed cycle gas lasers in which an active species is prepared by chemical reaction and the working medium is circulated repeatedly within a lightweight apparatus which is portable.
2. Description of the Prior Art
In the operation of many gas laser systems, the total mass of the working fluid which is passed through the optical cavity of the system is often considerable, particularly if the system is operated over a long duration of time. One of the early techniques used to reduce the overall consumption of gases in such systems was to recirculate all or a substantial portion of the working medium through the optical cavity, with suitable provision being made in some instances to remove detrimental species which found their way into the system as well as to provide means for adding fresh reactants as necessary. Concepts such as these are discussed in greater detail in U.S. Pat. No. 3,634,778, entitled Closed-Cycle Gas Laser System, U.S. Pat. No. 3,648,194, entitled Semiclosed Cycle Gas Laser System and U.S. Pat. No. 3,668,549, entitled Extended Closed Cycle Gas Laser System.
Laser system performance has been improved also by such techniques as changing either the type of reactant or the method for exciting the working medium. A description of early work relating to chemical laser systems was published by T. V. Jacobson et al in Transversely Pulse Initiated Chemical Lasers in the Chemical Physics Letters, Volume 8, No. 3, February 1971. The article describes producing laser radiation in a hydrogen fluoride system wherein fluorine atoms are derived from a fluorine containing molecule which is subjected to an electric discharge. These atoms are then allowed to react with molecular hydrogen to produce a chemically excited hydrogen fluoride laser species. This effort was elaborated upon in Transversely Pulse Initiated Chemical Laser:Atmospheric Pressure Operation Of An HF Laser published by T. V. Jacobson et al in the Journal of Applied Physics, Volume 42, No. 9, August 1971. A hydrogen fluoride laser capable of relatively high energy output pulses and using a mixture of sulfur hexafluoride and hydrogen which is subjected to a transverse electric discharge was described by H. Pummer et al in Investigation Of A 1-J Pulsed Discharge-Initiated HF Laser published in Applied Physics Letters, Volume 20, No. 9, May 1972. Jacobson et al disclose an extension of their earlier work in A High Repetition Rate Chemical HF Laser, IEEE Journal of Quantum Electronics, April 1973. These materials reflect the type of research effort that was being conducted in chemical laser systems particularly the hydrogen fluoride laser systems using sulfur hexafluoride as a source of fluorine.
A device which is based on some of this early work is described in U.S. Pat. No. 3,863,176, entitled Portable Chemical Laser issued to Martinez et al on Jan. 28, 1975. The system described is a laser device in which an excited gas is produced by chemical means and contained without exhausting to the atmosphere. Consumable cartridges are used to both supply the reactant materials and to receive all of the spent working medium after a single pass through the optical cavity. The system provides output energy for a few seconds and can be charged for reuse by changing both the feed cartridge and the pump cartridge.